The present invention relates to a semiconductor device and a manufacturing method thereof, and is preferably applicable to a semiconductor device including, for example, a solid-state image sensing element, and a manufacturing method thereof.
As a solid-state image sensing element, a CMOS image sensor using a CMOS (Complementary Metal Oxide Semiconductor) has been under development. The CMOS image sensor includes a plurality of pixels each having a photodiode and a transfer transistor. The photodiode and the transfer transistor are formed in the pixel region of a semiconductor substrate. On the other hand, in the peripheral circuit region of the semiconductor substrate, there are formed transistors forming a logic circuit, namely, logic transistors.
The manufacturing steps of a semiconductor device including a CMOS image sensor as a solid-state image sensing element have a step of doping ions into a semiconductor substrate in order to form a photodiode in a pixel region. In the ion doping step, for example, into a p type well formed on the upper surface side of the semiconductor substrate, for example, n type impurity ions are doped from the upper surface side of the semiconductor substrate, thereby to form an n type well in the inside of the p type well. This results in the formation of a photodiode having a pn junction between the p type well and the n type well.
Further, the manufacturing steps of a semiconductor device including a CMOS image sensor have a step of forming silicide layers in the pixel region and a peripheral circuit region. In the silicide layer formation step, after forming the photodiode in the pixel region, in the peripheral circuit region, silicide layers are formed at the upper surface of the gate electrode of a logic transistor and the upper surfaces of the source/drain regions on the opposite sides of the gate electrode.
Japanese Unexamined Patent Publication No. 2010-40636 (Patent Document 1) discloses the following technology: with the resist pattern left over the gate electrode of a transfer transistor in a pixel region as a mask, ions are doped into a semiconductor substrate, thereby to form a photodiode.